“It was arson with a professional fire accelerator,” Novartis spokeswoman Isabel Gueurra said in Bern.

One week earlier, someone dug up an urn containing the ashes of Vasella’s mother, who died in 2001, and took them from her grave in the eastern Swiss city of Chur, leaving behind the spray-painted message “Drop HLS Now” in red letters on the gravestone.

Graffiti slogans against Novartis and Vasella were also written on the church in Vasella’s village of Risch in central Switzerland about three weeks ago, the company said.

Novartis spokesman Satoshi Sugimoto said the company is convinced that British-based animal rights activists are behind a string of attacks on the company and its chief.

“We have no doubt that it is the same perpetrators,” Sugimoto said.

The animal rights group Stop Huntingdon Animal Cruelty has campaigned for years against the British testing laboratory Huntingdon Life Sciences, but on Tuesday the group denied any involvement in the Novartis attacks.

“It’s not true,” said Debbie Vincent, a volunteer with SHAC in Britain.

She said it was possible that a lone “antivivisectionist” had carried out the attacks, but said the group had done no more than demonstrate against Novartis.

Other animal rights groups in Britain also say Novartis has medical products tested on animals by Huntingdon, a company hounded in Britain and the United States for such work. Sugimoto, however, said the Basel-based Novartis has had no studies or any other work carried out by Huntingdon for years.

“That’s very strange,” said Vincent. “They’ve never told us that. Why don’t they tell us that directly?”

Juerg Buehler, director of the Swiss government’s Service for Analysis and Prevention, said there was no concrete indication who was behind the arson attack but said SHAC could not be ruled out. The group has been active in Switzerland for about five years.

“We still have too little solid evidence,” Buehler told Swiss Radio.

According to Novartis, attacks on houses and cars of the company employees as well as on Novartis property have grown in recent months.

In May, the company’s restaurant at sports facilities in nearby St. Louis, France, was damaged by fire.